A. Field of the Invention
The present invention generally relates to an industrial endoscope, or more particularly, to an endoscope with means for detecting rotation of a distal examining end.
B. Description of the Prior Art
The endoscope was developed as a medical instrument in the beginning. But, in recent years, it is used for industrial optical detecting means. For example, the endoscope is used for inspecting the inside of a reactor pile, a jet engine or a gas tank in which man cannot gain entrance.
For the above-said optical inspection, the distal examining end with an observing window is inserted into the examining portion and the distal examining end is operated by the grip end. With more detail, a plurality of wires are stretched between the distal examining end and the grip end. The wires are rotated at the grip end in order to twist the distal examining end and the flexible sheath. Accordingly, the observing window is opposed to the object. The image of the object is transmitted from the observing window to the grip end by way of image-transmitting optic bundles, and the image can be observed by an eye or be displayed at a monitoring television which is connected to the grip end.
In the rotation mechanism with a plurality of wires, the angle of rotation of the wires at the grip end and that of at the distal examining end does not strictly correspond. Accordingly, the state of rotation at the distal examining end cannot be made out from that at the grip end. That is to say, one rotation of the distal examining end may be caused by six rotations of the wire at the grip end in the first operation. But in the next operation, only five rotations of the wire may cause one rotation of the distal examining end.
In the prior art, means for detecting the direction and angle of rotation of the distal examining end are not provided in the endoscope, so that, the state of rotation cannot be made out when changing the direction of the observing window. In addition, the distal examining end can easily be damaged by excessively rotating the distal examining end in particular direction.